Heat treatment method and apparatus

Abstract

Heat treatment apparatus for annealing a reactor vessel includes an envelope having a plurality of insulated compartments each supplied with heated fluid from inlet ducts having nozzles in the compartments. The heated fluid passes out of the compartments via concentric tubular exhaust ducts. Heaters supplying the heated fluid are controlled by a mini-computer to ensure that a predetermined temperature profile is maintained across the heated section of the vessel.

What is claimed is: 
     
       1. Apparatus for heat treating a vessel, the apparatus comprising a plurality of inlet ducts; a plurality of exhaust ducts; and wall means defining a plurality of compartments for containing a heated fluid, said wall means preventing heated fluid in a compartment from contacting the vessel; each of said compartments having an exterior wall portion and being provided with at least one of said inlet ducts and at least one of said exhaust ducts for supplying and removing the heated fluid to and from the interior of the compartment, and said wall means being such that the exterior wall portion of each of said compartments is adjacent the exterior wall portion of at least one other one of said compartments whereby the wall portions form respective parts of a radiating surface for radiating heat onto a confronting interior wall or wall portion of the vessel; the apparatus further including means for supplying heated fluid to each of said inlet ducts and for controlling the thermal input of the heated fluid supplied to the respective inlet ducts, each of said compartments being independent of the other so that their internal temperatures may be individually controlled by controlling the thermal inputs of the heated fluid supplied to the respective inlet ducts, said means for supplying heated fluid and for controlling the thermal input of the heated fluid being operable to maintain a predetermined temperature profile across said radiating surface during the heat treatment process. 
     
     
       2. Apparatus according to claim 1, wherein said wall means define an envelope which is divided, by partitions, into the plurality of compartments. 
     
     
       3. Apparatus according to claim 1, in which said means for supplying heated fluid to each of said inlet ducts and for controlling the thermal input of the heated fluid supplied to the respective inlet ducts comprise a heater or heaters connected to the duct or ducts supplying the heated fluid to said compartments, regulating means for regulating the thermal outputs of each of said heaters, temperature sensing means for providing output signals representing temperatures measured at intervals spaced axially of the vessel and at the vessel wall surface, and computer means responsive to said output signals for controlling said regulating means. 
     
     
       4. Apparatus for heat treating a vessel, the apparatus comprising: (a) envelope means divided by partitions into a plurality of compartments, each of said compartments having a heat radiating wall portion which is adjacent the heat radiating wall portion of at least one other one of said compartments, whereby they form respective parts of a radiating surface for radiating heat onto a confronting wall portion of the vessel to be heat treated;   (b) inlet duct means connected to outlet nozzle means, each of said compartments having a plurality of said outlet nozzle means symmetrically situated therein and directed along the sides of a cyclic figure;   (c) exhaust duct means communicating with said compartments;   (d) insulating means insulating said compartments one from another except for said heat radiating wall portions of said compartments which are made of thermally conductive material to ensure rapid response to temperature change;   (e) means for supplying heated fluid to said inlet duct means, and   (f) means for individually controlling the thermal inputs of the heated fluid supplied to said inlet duct means in order to maintain a predetermined temperature profile across said radiating surface during the heat treatment of said vessel.   
     
     
       5. Apparatus according to claim 4, wherein said envelope means is cylindrical and said partitions extend radially of the cylindrical axis so as to divide said envelope means into a plurality of cylindrical chambers. 
     
     
       6. Apparatus according to claim 5, wherein said exhaust duct means are concentric tubes coextensive with said cylindrical axis. 
     
     
       7. Apparatus according to claim 6, wherein said means for supplying heated fluid to said inlet duct means comprises respective gas burner means, and wherein said means for individually controlling said thermal inputs comprises regulating means for regulating the outputs of said respective gas burner means. 
     
     
       8. A heat exchanger for use in apparatus for heat treating a vessel, the exchanger comprising a closed envelope divided by a plurality of partitions into a series of independent compartments for containing a heated fluid, said envelope preventing heated fluid in a compartment from contacting the vessel, said envelope having an axial extent with respect to which said partitions are transversely situated, an exterior wall portion of each compartment, other than said partitions, forming a respective part of a heat radiating surface, and one or more inlet ducts and one or more exhaust ducts communicating with each respective compartment for supplying and removing the heated fluid to and from the interior of the compartment, said outlet ducts extending co-axially with said axial extent of said envelope. 
     
     
       9. A method of heat treating a vessel comprising the steps of: (a) providing a series of independent, closed heating zones within the interior of the vessel for containing a heated fluid, each heating zone being bounded at the periphery thereof by part of a radiating surface;   (b) supplying heated fluid to each of said zones separately, and   (c) controlling the thermal input of the heated fluid to each zone so as to control its temperature and thereby provide a required temperature profile over said radiating surface and hence over a confronting interior wall or wall portion of said vessel.   
     
     
       10. A method according to claim 9, wherein said profile is a plateau-shaped. 
     
     
       11. A method according to claim 9, wherein a computer is programmed to control the supply of said heated fluid to each of said zones to maintain the required temperature profile. 
     
     
       12. A method according to claim 9, wherein said heat treatment is an annealing process in which the temperature of said radiating surface is gradually increased at a predetermined rate to an annealing temperature, the annealing temperature is maintained for a predetermined period, and the temperature of said radiating surface is gradually decreased at a predetermined rate. 
     
     
       13. Apparatus for heat treating a vessel, the apparatus comprising a plurality of inlet ducts; a plurality of exhaust ducts; and wall means defining a plurality of compartments; each of said compartments being provided with a plurality of said inlet ducts and at least one of said exhaust ducts, each of said inlet ducts terminating in outlets or nozzles which point in different directions, and said wall means being such that a wall portion of each of said compartments is adjacent a wall portion of at least one other one of said compartments whereby said wall portions form respective parts of a radiating surface for radiating heat onto a confronting interior wall or wall portion of the vessel; the apparatus further including means for supplying heated fluid to each of said inlet ducts and for controlling the thermal input of the heated fluid supplied to the respective inlet ducts, each of said compartments being independent of the other so that their internal temperatures may be individually controlled by controlling the thermal inputs of the heated fluid supplied to the respective inlet ducts. 
     
     
       14. Apparatus according to claim 13, wherein said outlets or nozzles are symmetrically situated within each respective compartment and are directed along the sides of a cyclic figure. 
     
     
       15. Apparatus for heat treating a vessel, the apparatus comprising a plurality of inlet ducts; a plurality of exhaust ducts in the form of concentric tubes and wall means defining a plurality of compartments; each of said compartments being provided with at least one of said inlet ducts and at least one of said exhaust ducts, and said wall means being such that a wall portion of each of said compartments is adjacent a wall portion of at least one other one of said compartments whereby said wall portions form respective parts of a radiating surface for radiating heat onto a confronting interior wall or wall portion of the vessel; the apparatus further including means for supplying heated fluid to each of said inlet ducts and for controlling the thermal input of the heated fluid supplied to the respective inlet ducts, each of said compartments being independent of the other so that their internal temperatures may be individually controlled by controlling the thermal inputs of the heated fluid supplied to the respective inlet ducts. 
     
     
       16. Apparatus for heat treating a vessel, the apparatus comprising a plurality of inlet ducts; a plurality of exhaust ducts; and wall means defining a plurality of compartments; each of said compartments being provided with at least one of said inlet ducts and at least one of said exhaust ducts, and said wall means being such that a wall portion of each of said compartments is adjacent a wall portion of at least one other one of said compartments whereby said wall portions form respective parts of a radiating surface for radiating heat onto a confronting interior wall or wall portion of the vessel; the apparatus further including means for supplying heated fluid to each of said inlet ducts and for controlling the thermal input of the heated fluid supplied to the respective inlet ducts, each of said compartments being independent of the other so that their internal temperatures may be individually controlled by controlling the thermal inputs of the heated fluid supplied to the respective inlet ducts, said compartments being insulated one from the other except for said wall portions which form respective parts of said radiating surface, said wall portions being made of thermally conductive material to ensure rapid response to temperature change.